AD FAA-2007-28920

The FAA is superseding an existing airworthiness directive (AD) that applies to certain Boeing Model 757-200, -200PF, and -200CB series airplanes. The existing AD currently requires repetitive inspections of the shim installation between the vertical flange and bulkhead, and repair if necessary. This new AD adds, for certain airplanes, an inspection for cracking of the four critical fastener holes in the horizontal flange, and repair if necessary. This AD results from reports of cracking in the pylon under bolts that appear to be undamaged during the existing AD inspections. We are issuing this AD to detect and correct cracks, loose and broken bolts, and shim migration in the joint between the aft torque bulkhead and the strut- to-diagonal brace fitting, which could result in damage to the strut and consequent separation of the strut and engine from the airplane.